Sonnette,
I am about to ding level 21 with my Dirge and looked at both classes closely before I picked Dirge. Both classes are group friendly, just in a slightly different way. Dirges work by making their group deal more damage. Whether by debuff, or enhancement songs that provide haste or make your group hit harder, proc more etc. your group is more efficient at what they do. On top of that - YOU are a damage dealer and have some respectable DPS that you can throw out yourself.
Troubadors are defensive in nature and thus they make the group hardier by singing defensive type songs. As far as crowd control goes - Troubador IS NOT your EQ bard. Most of what I have read and seen is that Troubador crowd control is pretty limited at best.
Having played a bard in EQ as well as a minstrel in DAOC, the Dirge is very much like the DAOC minstrel, while the Troubador is more like the EQ bard with alot of the fun stuff taken out. I realize that this is just my opinion and there will be 100 troubadors that will tell you differently, but I believe that the Dirge is both more versatile and fun.
Now, once troubador reaches level 50 and has thier high end charm, they may rule...however there is a lot of time between level 20 and 50 and I never judge my characters on their end game, just how much fun it takes to get there. My suggestion, take the one that sounds the most fun to you. After all, thats what the game is supposed to be about.
Andante Level 20 Dirge Guk